Amines Flashcards
What compound are amines derived from
Ammonia
What is the functional group of an amine
NH2
What is a primary amine
Where 1 carbon group is bonded to the N atom
What is a secondary amine
Where 2 carbon groups are bonded to the N atom
What is a tertiary amine
Where 3 carbon groups are bonded to the N atom
What is a quaternary ammonium salt
Where 4 carbon groups are bonded to the N atom, causing a positive charge on the molecule
What are non aromatic amines known as
Aliphatic amines
Give 3 uses of quaternary amine salts
Used to make shampoo, laundry detergents, washing up liquids
What are cationic surfactants
Quaternary amine salts which have a long ‘tail’/1 long hydrocarbon group
Explain how cationic surfactants act to remove oil and grease
The non-polar tail is attracted to the oil or grease.
The polar head will be attracted to the water.
This now allows the water and oil to mix and removes grease from clothing, skin. dishes etc
(essentially works by trapping the oil between the cationic surfactants, which allows the oil and the water to mix)
Explain how cationic surfactants act to soften hair
They have a positive ammonium ion which is attracted to the negatively charged fibres and hair.
This removes static so is used in conditioners etc
How do amines act as a base
They have a lone pair on the N which allows them to accept a proton (BLB)
How do protons bond to an amine
They bond via a dative covalent bond (both electrons come from lone pair on N)
How many bonds does N form when its neutral
3 (e.g.NH3)
What type of base is an amine
A weak base
List the strength of these amines from strongest to weakest
NH3
Primary aliphatic amines
Primary aromatic amines
Primary aliphatic amines
NH3
Primary aromatic amines
What determines the strength of an amine as a weak base
The availability of the lone pair of electrons on the nitrogen
Explain why primary aliphatic amines are the strongest base (out of the amines)
Alkyl groups have a positive inductive effect
This pushes electron density towards the N atom
Therefore the lone pair on the nitrogen is more available for protonation or donation
If a lone pair on an amine is being protonated, what is it acting as
A base
If a lone pair on an amine is being donated, what is it acting as
A nucleophile
Explain why primary aromatic amines are the weakest kind of base (out of the amines)
The lone pair on N is DELOCALISED INTO THE BENZENE RING
Therefore electron density on the N atom decreases
So the lone pair is less available for protonation or donation
What is electron density on the N atom in an amine dependent on
The type of group bonded to the N atom
What are the 2 ways to make a primary aliphatic amine
1: Reacting a halogenoalkane in excess NH3
2: Reducing a nitrile
Name and outline the mechanism by which ammonia is turned into a primary amine through 1-bromopropane
Nucleophilic substitution
Name and outline the mechanism by which a primary amine is turned into a secondary amine through 1-bromopropane
Nucleophilic substitution
Name and outline the mechanism by which a secondary amine is turned into a tertiary amine through 1-bromopropane
Nucleophilic substitution
Name and outline the mechanism by which a tertiary amine is turned into a quaternary ammonium salt through 1-bromopropane
Nucleophilic substitution
What are the reagent and conditions required for the amine nucleophilic substitution reactions
Reagent: Concentrated NH3
Conditions: High pressure & heat in a sealed container
What does using an excess of NH3 in the amine nucleophilic substitution reactions lead to
An excess of NH3 minimises further substitution
What does using an excess of halogenoalkanes in the amine nucleophilic substitution reactions lead to
Excess of halogenoalkanes favours further substitution
Name and outline the mechanism for the formation of a primary aliphatic amine from 1-bromopropane
Nucleophilic substitution
What is the downside of producing a primary aliphatic amine through reacting a halogenoalkane in excess NH3
Impure product
Why does producing a primary aliphatic amine through reacting a halogenoalkane in excess NH3 lead to an impure product
Primary amines still have a lone pair on the N which means they can further act as nucleophiles to form secondary amines, and even further to form tertiary amines and quaternary salts
What are the conditions and reagent for method 1(using LiAlH4) of producing a primary aliphatic amine through the reduction of a nitrile
Reagent: LiAlH4
Condition: In dry ether
What are the conditions and reagent for method 2 (catalytic hydrogenation) of producing a primary aliphatic amine through the reduction of a nitrile
Catalytic hydrogenation
Reagent: H2
Conditions: 150 degrees C
Catalyst: Nickel catalyst
Write an equation for the formation of a primary aliphatic amine using LiAlH4 from propanenitrile
Theres an extra alkyl group in product (just ignore it)
Write an equation for the formation of a primary aliphatic amine using H2 and a nickel catalyst from propanenitrile
What is the advantage of producing a primary aliphatic amine through the reduction of nitriles over reacting a halogenoalkane in excess NH3
Pure product
What are the 2 methods to prepare an aromatic amine (NITROBENZENE TO PHENYLAMINE)
NITROBENZENE TO PHENYLAMINE
Method 1: Using a reducing agent
Method 2: Catalytic hydrogenation
What are the 2 methods to prepare a primary aliphatic amine from the reduction of a nitrile
Method 1: Using Lithium aluminium hydride
Method 2: Catalytic hydrogenation
What are the reagent and conditions for method 1 (using a reducing agent) of preparing an aromatic amine in both a lab and industry
Lab:
Reagent: Concentrated HCl
Catalyst: Sn
Industry:
Reagent: Concentrated HCl
Catalyst: Fe
Both under reflux
Write an equation for method 1 (using a reducing agent) for the preparation of phenylamine from nitrobenzene
What are the reagent and conditions for method 2 (Catalytic hydrogenation ) of preparing an aromatic amine
Reagent: H2
Condition: 150 degrees C
Catalyst: Ni
Write an equation for method 2 (catalytic hydrogenation) for the preparation of phenylamine from nitrobenzene
What are aromatic amines used in
The manufacture of dyes
